A digital offset or digital architecture printing system may be used for printing with lithographic inks. Digital offset printing processes may include applying fountain solution to a surface of an imaging plate. The imaging plate may be arranged on an outer portion of an imaging cylinder. The imaging cylinder may be rotatable for bringing regions of the imaging plate surface to pass adjacent subsystems, including: a dampener for applying fountain solution; an imaging system for imaging or image-wise vaporization of fountain solution from select regions of the imaging plate; an inker for applying ink to the imaging plate surface; a transfer station from which an ink image is transferred to a printable medium; and a cleaner for removing residue from a surface of the image plate and preparing the surface to begin the process anew. After applying the fountain solution, an imaging system composed of a high power laser may be used to image-wise vaporize fountain solution from select regions of the surface. Light energy is absorbed by the imaging plate, which may comprise silicone, to locally heat and boil off fountain solution from the plate surface. The laser may be used for vaporizing the fountain solution at select surface regions in accordance with digital image data. Ink may be applied by the inker, and may be deposited on regions where fountain solution has been vaporized from the imaging plate. Conversely, ink may be rejected by regions of the imaging plate surface where fountain solution remains. A resulting image is transferred at the transfer station to paper or other suitable media by way of pressure.
For the imaging step, an imaging system may be used that is configured to produce an output beam that spans the operative width of an imaging plate surface. Due to the high output power requirement, it is difficult to construct a suitable imaging system from a monolithic imager. It is much more feasible and economical to construct the imaging system from an array of imagers, each possessing a light beam width that is smaller than the imaging plate operative width. To construct the imaging system, multiple imagers or illumination modules may be configured to “stitch” together a light beam having a useful process width for a longer total image.
Current imaging systems use illumination modules having light guides with mirrors or prism designs to homogenize and deliver light beams onto spatial light modulators, such as digital mirror devices (DMD). These current illumination modules require lateral space and axial rotation of the illumination system. This prevents side-by-side stacking of the illumination modules, which is necessary in high resolution printing systems having illumination systems with light sources and DMDs that require side-by-side stacking of the illumination modules for stitching of high resolution images from each module to form a longer total image width.